Known hitherto as such a VTR system are 3/4-inch VTRs and VHSVTRs and, in 3/4-inch VTRs, in order to allow use of two, large and small, classes of cassettes, each of said cassettes is arranged to have guide channels so as to be guided to a predetermined position in a cassette garage. On the other hand, in VHSVTR cassettes, an adapter is attached to a smaller cassette so as to be used similarly to a larger cassette and the smaller cassette is guided to a predetermined position in a cassette garage.
Here, a prior arrangement of the VHSVTR system will be described with reference to FIGS. 18 through 24.
A structure of a VTR is illustrated in FIG. 18, in which numeral 1 represents a tape-cassette garage (which will hereinafter be referred to as cassette garage) for guiding insertion of a cassette. The cassette garage 1 has a frontage 2 whose dimension is slightly greater in length and height than that of the larger cassette and is provided with a pair of holes 3 and a projection 4 at its bottom surface 1a and equipped with a pair of cut-and-raised portions 5 at the front edge of its bottom surface 1a. In addition, the cassette garage 1 is arranged to be movable upwardly and downwardly by means of a sliding mechanism, not shown. On the other hand, below the cassette garage 1 are provided a pair of reel bases 7 which are fixed on a bedplate 6 and which are rotated by means of a motor, not shown, so that the reel bases 7 are fitted in the holes 3 in response to downward movement of the cassette garage 1.
FIG. 19 is an illustration of a structure of a large cassette 8. The body 9 of the large cassette 8 is made up by engagement and fastening of an upper case 9a and a lower case 9b and encases a pair of tape reels 10. At the front face of the cassette body 9 is defined an opening portion 11 and along the opening portion 11 is stretched a magnetic tape (not shown) wound around the tape reels 10. Numeral 12 is an opened and closed cover provided rotatably with respect to the case body 9 for covering from the outside the magnetic tape (not shown) stretched along the opening portion 11. At a substantial center portion of the opened and closed cover 12 is provided a recess 13 for prevention of a reverse-insertion and, when as shown in FIG. 20 the large cassette 8 is inserted with the upper portion and lower portion thereof being reversed, the projection 4 and the recess 13 come into contact with each other so as to prevent the insertion in advance. Numeral 14 represents a guide channel provided at the bottom surface of the cassette body 9 and numeral 15 designates a safety lug. FIG. 21 shows a structure of a small cassette 16. The body 17 of the small cassette 16 is made up with engagement and fastening of an upper case 17a and a lower case 17b and encases a pair of tape reels 18, 19. On the periphery of a lower flange 19a of the tape reel 19 are formed teeth 20 which are exposed from a side surface of the cassette body 17. Numeral 21 is an opened and closed cover provided on the case body 17 for covering a magnetic tape (not shown) wound around the tape reels 18 and 19 from the front side.
FIG. 22 illustrates the structure of a cassette adapter 22, whose outer dimension is equal to that of the large cassette 8, for encasing the small cassette 16. The cassette adapter 22 has the same outer dimension as the large cassette 8 and, at the left side, has a space 23 for encasing the small cassette 16. In the space 23 are provided arms 25 each of which has a guide roller 24 planted at one end portion thereof for stretching the magnetic tape (not shown) wound around the reels 18, 19 up to the same position as in the case of the large cassette. Numeral 26 depicts a guide channel. Numeral 27 represents an opened and closed cover for holding the inserted small cassette 16 by depression from the upper side, the arms 25 being automatically operated in response to closing of the opened and closed cover 27. On the other hand, at the right side thereof is provided a rotatable first rotating body 28 whose configuration is substantially similar to that of the reel 10 of the large cassette 8. On the periphery of a flange 28a of the first rotating body 28 are formed teeth (not shown) which are in turn engaged with second and third rotating bodies 29 and 30 which have respectively teeth similar to those of the first rotating body 28 and which are arranged rotatably, the third rotating body 30 being exposed into the space 23. Numeral 31 is an opened and closed cover provided so as to cover the stretched magnetic tape (not shown) from the front side, and at a substantial center portion of the opened and closed cover 31 is provided a recess 32 for prevention of error-insertion. Numeral 33 is a safety lug.
With respect to the above-mentioned arrangement, a description of the case of initially mounting the large cassette 8 will be made with reference to FIG. 23. In FIG. 23, the large cassette 8 is moved in a direction indicated by an arrow with the opened and closed cover 12 being advanced and, in response to reaching the inside of the frontage 2, is guided and inserted by means of the engagement of the guide channel 14 with both side surfaces 1b, 1c and projection 4 of the cassette garage 1. Termination of the insertion thereof into the cassette garage 1 is made by coming into contact with the cut-and-raised portions 5. Thereafter, the entire cassette garage 1 is moved downwardly whereby the reel bases 7 are inserted into the holes 3 to be engaged with the reels 10, resulting in the recording and reproducing state. Second, a description of the case of mounting the small cassette 16 will be made with reference to FIG. 24. Here, the description of the process after the mounting on the cassette garage 1 will be omitted because it is the same as in the case of the mounting of the large cassette 8. In FIG. 24, the opened and closed cover 21 of the small cassette 16 is first full-opened and then encased in the reception space 23 of the cassette adapter 22 so that the opened and closed cover 21 of the small cassette 16 and the opened and closed cover 12 of the cassette adapter 22 are directed to same direction. After encased, the opened and closed cover 27 of the adapter 22 is set to the closed state. With the above processes it results in the same use state as the large cassette and the recording and reproducing can be made in accordance with the same procedure as the mounting of the large cassette.
However, in the above-described arrangement, an exclusive use adapter is required for use of the small cassette and the provision of the adapter results in cost-increase and further results in being troublesome in operation. In addition, the structure of the small cassette itself results in poor airtightness because it is required that a portion of teeth is exposed due to the relation between the adapter and drive means, and the poor tightness allows insertion of dust therefrom and causes increase of drop out, deterioration of the image quality and so on. Therefore, the above-mentioned large and small cassette system is not adequate.